The photocatalytic oxidation of the organic pollutants with TiO(2) as photocatalyst has been widely studied in the world, and many achievements have been made. The degradation of pollutants is highly related to the photocatalytic activity of TiO(2). It is demonstrated that doping ions to TiO(2) is one way to enhance the photocatalytic activity of TiO(2). In this paper, Zn(2+)-doped TiO(2) nanoparticles were prepared through sol-gel and solid phase reaction methods, characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The photocatalytic activity of the elaborated powders was studied following the degradation of Rhodamine B. The results showed that the photocatalytic activity of Zn(2+)-doped TiO(2) prepared by sol-gel method is close to that of pure TiO(2) particles, however, the photocatalytic activity of Zn(2+)-doped TiO(2) prepared by solid phase reaction method is much higher than that of pure TiO(2) particles. The most efficient degradation of Rhodamine B was found with TiO(2) particles doped with 0.5% Zn(2+) in mole and calcined at 500 degrees C. Also the reason for the enhancement of the photocatalytic activity of TiO(2) by Zn(2+) doping through solid phase reaction method was discussed. 相似文献
Organophosphate pesticides (OPPs) are one type of the most massively used pesticides and ubiquitously detected in aquatic environments, which may pose potential risks to the aquatic organisms and human health. In the present study, the spatiotemporal distribution and potential risks of OPPs were investigated in overlying water and surficial sediments from urban waterways of Guangzhou. For all studied sites, in general, four target OPPs (i.e., malathion, chlorpyrifos, terbufos, and diazinon) were present in the overlying water, with malathion and chlorpyrifos as major components. Higher concentrations of the four OPPs were found for the water and sediments collected in the dry season compared to the wet season, possibly because of the dilution effect of heavy rains. The results of Pearson’s analyses and principal coordinate analyses (PCoA) suggested similar sources for target OPPs in the water and sediments across the Guangzhou urban waterways. Potential ecological risks of the OPPs to three representative taxons (algae, aquatic invertebrates, and fish) were evaluated via toxic units (TUs) and risk quotients (RQs), while risk assessment on human health was performed using hazard index (HI). Although TU results showed no acute risks to the aquatic organisms in the overlying water and surface sediments, RQ results of the mixture showed high risks to the aquatic invertebrate and fish in all water samples. Individual HI values and cumulative HI values were on the order of 10?6–10?3 for children and adults, suggesting no potential risks to either children or adults through drinking and bathing.
